Rinse added fabric conditioning compositions are well known. Typically, such compositions are provided as a liquid in a plastics bottle which requires the consumer to dose the correct amount of the fabric softening composition from the bottle into the dispensing drawer of a washing machine.
The problem with conventional liquid fabric softeners provided in a bottle or other such package is that there is always a risk of underdosing or overdosing the rinse conditioning composition into the dispenser drawer of a washing machine resulting in a unsatisfactory or undesired level of softening being provided to fabrics. There is also the problem of spillage of the ingredients when pouring the product from the package into the dispensing drawer of a washing machine.
Therefore, it is desirable to provide a rinse conditioning composition which is convenient to use and guarantees that the correct amount of fabric softening composition is dosed into the rinse cycle. It is also desirable to avoid the problem of spillage of the product associated with the dispensing of conventional rinse conditioners from a bottle or the like.
Water soluble packages are known in the detergent and agrochemical industries and generally comprise either vertical form-fill-seal (VFFS) envelopes or thermoformed envelopes. In one of the VFFS processes, a roll of water soluble film is sealed along its edges to form a tube, which tube is heat sealed intermittently along its length to form individual envelopes which are filled with product and heat sealed. The thermoforming process generally involves moulding a first sheet of water soluble film to form one or more recesses adapted to retain a composition, such as for example a solid agrochemical composition, placing the composition in the at least one recess, placing a second sheet of water soluble material over the first so as to cover the or each recess, and heat sealing the first and second sheets together at least around the recesses so as to form one or more water soluble packages.
Cleaning products are traditionally often liquids, viscous or thin, such as known for personal cleaning (bath and shower liquids and shampoos) or for domestic cleaning (hand dish wash and other hard surface cleaning, laundry-cleaning etc.). Other products are solids, such as powders, granules, small capsules (up to 2 mm diameter) or more recently tablets, for laundry and machine dish wash, and soap bars for skin cleaning. Recently, so called unit dose products are experiencing an increasing success with consumers, because they eliminate the need for manipulating, and possibly spilling, liquids or powders and simplify the use of a correct dose of the product for the required purpose. Examples thereof are the laundry and machine dish wash tablets mentioned above and recently described in F. Schambil and M. Böcker, Tenside Surf. Det. 37 (2000) 1.
Many types of water soluble packages are known, including packages made from polyvinyl alcohol (hereinafter referred to as “PVOH”) film. A wide variety of different materials can be packaged in such films, including liquid materials.
EP-A-518689 discloses a containerisation system for hazardous materials (for example pesticides) comprising a PVOH film enclosing a composition comprising the hazardous material, water, an electrolyte and optional other materials. The electrolyte is added to reduce the solubility of the film to prevent its dissolution by the packaged composition.
WO9737903 discloses films for the encapsulation of agro-chemicals. There is no suggestion of films designed to respond to surfactant concentration.
EP-B-389513 discloses concentrated aqueous syrups (mainly foodstuffs but other materials such as detergents are mentioned) inside PVOH packages, the concentration of the syrup being effective to prevent dissolution of the package by the packaged composition.
EP-A-700989 discloses a unit packaged detergent for dish washing, the package comprising a detergent composition wrapped in PVOH film, wherein the film protects the detergent from dissolution until the main wash cycle of the dish washing machine.
WO-A-97/27743 discloses an agrochemical composition packaged in a water soluble sachet, which can be PVOH.
GB-A-2118961 discloses bath preparations packaged in PVOH film, while EP-B-347221 relates to water-soluble sachets of phytosanitary materials which are packaged in a secondary water-insoluble pack with a humid environment being maintained between the two.
EP-A-593952 discloses a water soluble sachet of PVOH with two chambers and a treatment agent for washing inside each chamber.
EP-A-941939 relates to a water soluble package, which can be PVOH, containing a composition which, when dissolved, produces a solution of known composition.
GB-A-2305931 discloses a dissolvable laundry sachet and BE-9700361 relates to a water soluble unit-dosed cleaning agent, especially for cleaning hands.
DE-29801621 discloses a water soluble unit dose for dishwashing machines.
EP-B-160254 relates to a washing additive comprising a mixture of detergent constituents in a PVOH bag. The detergent comprises nonionic surfactant and a quaternary ammonium compound. U.S. Pat. No. 4,846,992 discloses a double-packaged laundry detergent wherein the inner package is water-soluble and can be PVOH.
EP-B-158464 relates to a detergent mull packaged in PVOH and DE-A-19521140 discloses a water soluble PVOH sachet containing a detergent composition.
FR-2601930 relates to a water soluble sachet containing any substance, particularly a pharmaceutical.
A variety of water soluble PVOH films are also known. For example, EP-B-157162 relates to a self-supporting film comprising a PVOH matrix having rubbery microdomains dispersed therein.
WO-A-96/00251 relates to an amphipathic graft copolymer comprising a hydrophobic backbone with grafting sites to which are grafted a hydrophilic polymer prepared from a hydrophilic monomer containing stabilising pH independent ionic groups.
GB-B-2090603 relates to a water soluble film comprising a uniform mixture of partially hydrolysed polyvinyl acetate and polyacrylic acid.
WO-A-97/00282 relates to a water soluble film combining two polymeric ingredients S and H where S is a soft acid-functional olefinic addition copolymer having a Tg less than 20° C. and H is a hard acid-functional olefinic addition copolymer having a Tg less than 40° C. The ratio of S:H is from 90:10 to 65:35 and the acid functionalities are at least partially neutralised to render the film water soluble.
EP-B-79712 relates to a laundry additive for discharge to a wash containing borate ions. The additive is enclosed within a film of PVOH which is plasticised and has as a solubiliser either a polyhydroxy compound (such as sorbitol) or an acid (such as polyacrylic acid).
EP-B-291198 relates to a water soluble film containing an alkaline or borate-containing additive. The film is formed from a copolymer resin of vinyl alcohol having 0–10 mole % residual acetate groups and 1–6 mole % of a non-hydrolysable anionic comonomer. FR-2724388 discloses a water soluble bottle, flask or drum made from PVOH which is plasticised with 13–20% of plasticiser (such as glycerol) and then moulded.
The specifications of International Patent Applications WO-A-00/55044, WO-A-00/55045, WO-A-00/55046, WO-A-00/55068, WO-A-00/55069 and WO-A-00/55415 disclose water soluble packages containing a fluid substance (defined as a liquid, gel or paste) which is a horizontal form-fill-seal (HFFS) envelope. These packages comprise a body wall portion having internal volume and which is preferably dome-shaped, formed from a first sheet, and a superposed base wall portion, formed from a second sheet, seded to the body wall portion.
A PVOH package containing a liquid laundry detergent composition comprising from about 10% to about 24% by weight of water (but 3.57% in the sole example) is disclosed in U.S. Pat. No. 4,973,416.
EP0283180 discloses the preparation of very fast dissolving films with a high degree of hydrolysis.
WO-A1-97/19961 discloses fast solubility polymers, made from PVOH co-polymerized with carboxylate moieties, and have some degree of lactonization. These materials dissolve quickly in detergent solution. There is no reference or suggestion to control of solubility using washing surfactants.
EP0284334 relates to films comprising a blend of PVOH and alkyl celluloses with a metal salt, such as borate, to produce a triggered pouch. The alkyl cellulose is present to respond to temperature such that at low rinse temperatures it is more soluble than at the higher temperatures associated with the wash cycle. The borate cross linking provides pH sensitivity. Furthermore, this document discloses that anionic surfactants have very little effect on or even increase the rate of dissolution of the film.
GB2358382 relates to rigid blow molded components made from PVOH.
AT408548 concerns PVOH materials that contain builders for the improvement of detergency during the wash cycle.
When formulating a liquid unit dose product of the kind wherein a substantially non-aqueous formulation is encapsulated in a water soluble film, probably the most difficult challenge is to preserve the physical integrity and stability of the film. One approach to this problem is disclosed in WO-A1-01/79417, which involves substantially neutralising, or over-neutralising any acidic components in the liquid composition, especially any fatty acids and/or acid precursors of anionic surfactant. However, this approach is specific to encapsulation using a water-soluble film based on PVOH which includes comonomer units having carboxyl functionality.
Preservation of the integrity of films which contain fabric softening compositions for use in the rinse cycle is particularly challenging since commercial softening compositions are generally aqueous and tend to interact undesirably with water soluble packaging causing a weakening of the film and potentially premature breakage, e.g. during storage.
One way of addressing this problem is disclosed in U.S. Pat. No. 4,765,916 which involves providing a cross-linked polymeric water soluble film, preferably a borate.
Where the package is to deliver a fabric softening composition, it is important that the contents are delivered primarily during the rinse cycle.
In the case of so-called “top-loading” washing machines where the fabric conditioning product is typically dosed directly into the drum of the washing machine, this usually requires that the consumer to be present both at the beginning of the wash cycle and at the beginning of the rinse cycle to dose the wash and rinse products respectively.
Accordingly, it is desirable to be able to provide a product which can be dosed into the washing machine drum at the beginning of the wash cycle but does not disperse or release its contents until the rinse cycle.
One way of addressing this problem is set out in WO-A1-02/102956, where a water soluble package is provided which is soluble in response to, for instance, the change in pH and/or ionic strength from the wash liquor to the rinse liquor. However, the variety of machines and wash conditions means that changes in pH and/or ionic strength can vary enormously. Therefore, it is also desirable to provide a water soluble package which can be dosed into the wash cycle and which is triggered in the rinse cycle by an alternative means.
WO-A-01/85892 discloses highly concentrated conditioners with PVOH film receptacles which are added to the rinse compartment of the dosing drawer. The receptacle enters the rinse bath when the rinse cycle starts.
WO-A-00/51724 discloses the use of molecular sieves for controlled release of fabric treatment products.
WO-A-00/06688 relates to PVOH films which are modified with an amine group. The film releases its contents due to a change in pH during the laundry cycle.
DE-A-2749555 discloses a two fold laminate with a washing pouch, released during the rinse. However, an insoluble bag remains after the laundry cycle is complete. Furthermore, the polymers discloses therein are not hydrophobically modified.